![File:A diagram representing a convex mirror, which shows its focal point, focal length, center of curvature, and the principal axis.png - Wikipedia File:A diagram representing a convex mirror, which shows its focal point, focal length, center of curvature, and the principal axis.png - Wikipedia](https://upload.wikimedia.org/wikipedia/commons/b/b6/A_diagram_representing_a_convex_mirror%2C_which_shows_its_focal_point%2C_focal_length%2C_center_of_curvature%2C_and_the_principal_axis.png)
File:A diagram representing a convex mirror, which shows its focal point, focal length, center of curvature, and the principal axis.png - Wikipedia
Gabriel Peyré on X: "The subdifferential is the set of slopes bellow the graph of a convex function. It is a set-valued monotone map. Generalize the gradient to non-smooth functions. The most
![Gabriel Peyré on X: "Oldies but goldies: J. P. Boyle and R. L. Dykstra, A method for finding projections onto the intersection of convex sets in Hilbert spaces, 1986. Dykstra's algorithm is Gabriel Peyré on X: "Oldies but goldies: J. P. Boyle and R. L. Dykstra, A method for finding projections onto the intersection of convex sets in Hilbert spaces, 1986. Dykstra's algorithm is](https://pbs.twimg.com/media/FYauLmNWQAAYbJv.jpg:large)
Gabriel Peyré on X: "Oldies but goldies: J. P. Boyle and R. L. Dykstra, A method for finding projections onto the intersection of convex sets in Hilbert spaces, 1986. Dykstra's algorithm is
![Gabriel Peyré on X: "The subdifferential is the set of slopes bellow the graph of a convex function. It is a set-valued monotone map. Generalize the gradient to non-smooth functions. The most Gabriel Peyré on X: "The subdifferential is the set of slopes bellow the graph of a convex function. It is a set-valued monotone map. Generalize the gradient to non-smooth functions. The most](https://pbs.twimg.com/media/DZmcg-MX4AAKPnn.jpg:large)